Rolling-contact bearings are composed of a rolling element interposed between an inner and outer race. In a cageless ball bearing a number of balls rotate freely between inner and outer circular races, thereby permitting the races to independently rotate with respect to each other. The races are grooved to captively accept the balls. The balls are disposed between the races so that the space between the races is substantially circumferentially filled with balls. In another type of ball bearing, separators, sometimes called cages or retainers, are used to evenly space the balls from each other around the race circumference.
Various ball bearing designs are well known in the art. For example, U.S. Pat. No. 3,425,759 shows a gyromotor bearing in which a plurality of sintered polyamide resin, lubricant-impregnated balls are intercalated between the solid steel balls of the bearing.
U.S. Pat. No. 4,500,144 defines a bearing member which includes a series of carbon separators. As the separators wear, the space between the balls increases as is shown in FIG. 13. Notice that the radial angle between balls 14n and 14 is about 80 degrees.
U.S. Pat. No. 5,234,272 pertains to a plurality of rollers 4 are arranged between the inner and outer races 2 and 3 so that the distances between the rollers can be freely changed without a retainer. Since there is no retainer, any abrasion of the retainer due to the frictions between the rollers and the retainer is not caused, the number of the rollers can be increased, and the carrying capacity can be increased so that the roller bearing with a longer life time can be obtained. In one embodiment one or more rollers are removed to reduce friction and prolong the life of the bearing.
U.S. Pat. No. 5,309,529 discloses a bearing arrangement for a radial bearing in an acceleration-proof gyroscope.
U.S. Pat. No. 5,443,317 comprises a rolling bearing having balls of different diameters. The balls have limited movement within a pocket.
French Pat. No. 484,410 is directed to a ball bearing which has alternating large and small balls. The ball bearing has one ball less than a full complement.
A cageless ball bearing is defined as a ball bearing which does not include any form of cage, retainer, or separator to hold the balls apart, but rather a ball bearing in which the balls are free to travel between the inner and outer races in abutting relationship. In a conventional cageless ball bearing, the bearing has a “full complement” of balls. A full complement of balls is defined as the maximum number of balls that will circumferentially fit between the inner and outer races. That is, there is not enough room in which to circumferentially fit another ball. There is however a very small circumferential gap between balls so that the balls are free to move circumferentially around the races, and are also free to rotate within the races. The total circumferential gap between all balls (also defined herein as the “maximum circumferential gap”) is less than the diameter of one ball, and typically accounts for only about a ten degree or less open sector. This is desirable because by having the balls tightly packed and therefore evenly distributed around the circumference of the races, the axial forces exerted upon the bearing are always balanced, thereby resulting in smooth vibration-free performance.
However, because the balls of the conventional cageless ball bearing are tightly packed around the circumference of the bearing, the conventional cageless ball bearing is highly susceptible to seizing or binding when foreign particles such as sand, rock, chips, debris, and the like are encountered. Particles can wedge into and completely fill the small circumferential gaps between adjacent balls and prevent the balls from both moving circumferentially around the races, and from rotating within the races. When this happens the bearing seizes, usually rendering the parent machine inoperable.
It is toward the solution of this seizing problem to which the teachings of the present invention are directed.